Recent development in gravity and bathymetry mapping from satellite altimetry - The DTU10 fields. Ole B. Andersen

Transcription

1 Recent development in gravity and bathymetry mapping from satellite altimetry - The DTU10 fields Ole B. Andersen

2 Outline Global Altimetric gravity from Satellite (sea surface height) Double retracking / repicking The Arctic Ocean Completing global Coverage Accuracy, Coherency Bathymetry + Bouguer Anomaly estimation. DTU Space: Proprietory gravity fields Examples Arctic / Polar regions / East Greenland Florida Keys 2 DTU Space, Technical University of Denmark

3 Main Offshore Sedimentary Basins From KMS02 -> DTU10 Focused on improving gravity field in Shallow water regions Polar regions 3 DTU Space, Technical University of Denmark

4 Mapping the sea surface from space Using radar. 4 DTU Space, Technical University of Denmark

5 Gravity from Sea surface heights DTU10 Features - Truly global gravity field (90 S-90 N) km resolution grid (1 minute = 1/60 ) - Based on retracked / repicked Satellite altimetry h = N + MDT + n(t) Δg N N = γ 2γ r r 5 DTU Space, Technical University of Denmark High Res gravity on the ocean surface

6 Double Waveform retracking/repicking First Retrack: Gain more data and better spatial coverage Second Retrack: Enhanced SSH estimation (repicking/retracking) First Retracking: EAPRS rule-based Expert System (P. Berry, Leicester University UK): Identify 12 different waveform type (ocean, ice, patch, specular..) Retrack using specially designed retrackers. Waveform Globally: 9% gain but focused on Polar and Near Shore regions. 6 DTU Space, Technical University of Denmark

7 Polar Regions: Heavy Gain in Coverage ORIGINAL ESA ERS-1 DATA Retracked ERS-1 1Hz 7 DTU Space, Technical University of Denmark Data KMS02 DNSC08/DTU10 Standard / 4.0 Max

8 Old Global marine gravity field (i.e. Sandwell/Smith lim: 72N) ERS-1/2 Radar up to 82 N (KMS02) Polar Gap: ERS2/ENVISAT + ICESAT + ArcGP ICESAT laser between 80 N and 86 N ArcGP complete Polewards coverage above 86 N 8 DTU Space, Technical University of Denmark

9 DTU 10 Free Air Gravity Anomalies Land fill in: EGM2008 gravity anomalies 9 DTU Space, Technical University of Denmark

10 Coastal regions heavily improved A ll > obs Std (KMS02) 10 DTU Space, Technical University of Denmark Std (SS 16.1) Purple (0-20 m DEPTH) Dark Blue (20-50 m) Light Blue ( m) Green ( m) Yellow ( m) Red + Pink ( m) Std (DNSC08) KMS02-DNSC08 %Improvement 48

11 Gulf of Mexico Florida Keys Strong currents Steep Bathymetry Large differences KMS02, DNSC08,SS marine Obs Lots of marine Gravity Difference KMS02-DNSC08 11 DTU Space, Technical University of Denmark Std Dev (mgal) KMS SS 16.1 / SS / 3.12 DTU Difference SS16.1 DNSC08

12 Δg Error estimate mgal 12 DTU Space, Technical University of Denmark

13 Coherence Spectrum (Caribbean) 1 0,9 DNSC08 KMS02 0,8 800 km Marine Coherence 0,7 0,6 0,5 0, km gravity profile RMS signal 32 mgal, RMS Diff: 2.86 mgal 0,3 0,2 0, Wavelength (km) 13 DTU Space, Technical University of Denmark

14 DNSC08 Bathymetry Improved GEBCO 1min bathymetry using DTU10 Gravity Consistent 1-min grid to DNSC08 Gravity For easy estimation of Bouguer gravity anomalies. Example DNSC08-Bouguer by D. Fairhead GTECH 14 DTU Space, Technical University of Denmark

15 Whats Next Cryosat II Delay Dobbler Advantages: Higher accuracy Higher Track resolution (300 m) Stabil accuracy (no sig wavehgt) And Then: Sentinel 3 15 DTU Space, Technical University of Denmark

16 Off+Onshore Northeast Greenland DTU Space assist in: Potential field research & Proprietary Field Generation Optimal merging of data Global grids + Survey data Regional subset (Q-control) DNSC08 Bathymetry Bathymetry prediction Global grids + Survey data Bouguer Anomaly prediction Merging Gravity + Bathymetry Example of merging DNSC08 gravity Field with airborne data off eastcoast Of Greenland for exploration 16 DTU Space, Technical University of Denmark

17 Summary DNSC08 / DTU10 Resolution: 1 minute by 1 minute (2 km by 2 km) True global gravity field (90 S to 90 N) Internet point of download: FTP: ftp.spacecenter.dk/pub/dtu10 WWW: Proprietory grids / quality control / data services etc: Contact Ole B. Andersen oa@space.dtu.dk Additional Consistent Products Mean Sea Surface / MDT Altimetric derived Bathymetry Error/Accuracy field. Aknowledgement: P. Knudsen (DTU Space). P. Berry, J. Freeman (De Montfort) S. Kenyon, 17 DTU Space, N. Technical Pavlis(NGA) University of Denmark

18 Thank you 18 DTU Space, Technical University of Denmark